JPH05333706A - Color image forming device - Google Patents

Abstract

PURPOSE:To provide the color image forming device where a great reduction of the cost and miniaturization can be carried out and an excellent image can always be obtained by eliminating a cleaning device with which an intermediate transfer body can be separated from or brought into contact. CONSTITUTION:After the image forming action is completed, bias of the reverse polarity to toner is impressed on a photosensitive body 1 and bias of the same polarity to the toner is impressed on the intermediate transfer body 2 in a part of contact of the photosensitive body 1 as a latent image carrier and the intermediate transfer body 2, furthermore, a great cost reduction and miniaturization can be carried out and the excellent image can always be obtained by eliminating the conventionally required cleaning device which can be separated from or brought into contact to the device to clean the intermediate transfer body 2 by having the residue toner on the intermediate transfer body 2 stuck again to the photosensitive body 1 by having the residue toner on the intermediate transfer body 2 electrified again by an electrifying device for residue toner 15.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a toner image formed on a latent image bearing member such as a photoconductor or an insulator, which is successively transferred onto an intermediate transfer member to form a composite image. The present invention relates to a color image forming apparatus for finally collectively transferring an image onto a transfer material.

[0002]

2. Description of the Related Art In recent years, transfer type color image forming apparatuses have been
A method is widely used in which toner images of different colors are sequentially formed on a latent image carrier such as a photoconductor or an insulator, and the respective toner images are multi-transferred onto a transfer material.

For example, in JP-A-55-90972, as one method of transfer system, individual yellow, cyan, magenta, and black toner images formed on a latent image carrier such as a photoconductor or an insulator are described. A method has been proposed in which the toner images of three or four colors formed on the intermediate transfer body are collectively transferred onto a transfer material by transferring the toner images on the intermediate transfer body in the form of a drum or a belt, which is an intermediate image carrier. There is.

A conventional color image forming apparatus will be described below with reference to the drawings. FIG. 2 is a block diagram of a conventional color image forming apparatus. Reference numeral 1 in the figure denotes a photoconductor as a latent image carrier having a photoconductive layer on the surface. Around the photoconductor 1
A charger 7 for uniformly charging the photoconductor 1, a laser scanner for writing to form an electrostatic latent image on the photoconductor 1, or an optical system 4 such as an LED head. Developing devices 3a to 3d for forming an image are arranged. The developing devices 3a to 3d contain toners of yellow, magenta, cyan, and black colors.

The photosensitive member 1 is in contact with the belt 2a of the intermediate transfer member 2 on the downstream side of the developing device 3a with respect to its rotating direction. The belt 2a of the intermediate transfer member 2 is made of a material in which a substance such as carbon is dispersed in a resin and the resistance value is adjusted from 10 ⁵ Ω to 10 ¹² Ω. Reference numeral 9 denotes a cleaning device for cleaning the residual toner on the belt 2a of the intermediate transfer member 2, which is composed of a blade made of synthetic resin such as urethane, a magnetic brush, and a conductive brush. The cleaning device 9 has a structure that can be brought into and out of contact with the belt 2a of the intermediate transfer member 2.

Reference numeral 11 denotes an intermediate transfer device for transferring the toner from the photosensitive member 1 to the belt 2a of the intermediate transfer member 2, which disperses carbon or the like in a corona discharger to which a high voltage is applied, a metal roller or a synthetic resin. It is composed of a conductive roller to which a high voltage is applied, and is arranged inside the intermediate transfer body 2 at a position where the intermediate transfer body 2 and the photoconductor 1 are in contact with each other. Reference numeral 5 denotes a transfer device for transferring toner from the belt 2a of the intermediate transfer member 2 to the transfer material 13. A cleaning device 6 for the photoconductor 1 is arranged downstream of the position where the photoconductor 1 and the belt 2a of the intermediate transfer body 2 are in contact with each other.

Reference numeral 8 designates the transfer material 13 as the belt 2 of the intermediate transfer member 2.
A registration roller 10 that conveys the toner image on the transfer material 13 at the same timing as the composite image on the transfer material 13a
A fixing device for fixing the transfer material 13 and a transfer material cassette 12 for accommodating the transfer material 13.

The operation of the color image forming apparatus configured as described above will be described below.

First, the photoconductor 1 having a high resistance in the dark area.
Is uniformly charged by a charger 7 that generates corona ions by corona discharge, and then the photoconductor 1 is exposed according to image data by an optical system 4 composed of a laser scanner or an LED head. An electrostatic latent image of the yellow component is formed on top. Next, the yellow toner image on the photoconductor 1 is obtained by developing the electrostatic latent image of the yellow component on the photoconductor 1 with the yellow toner of the developing device 3a. Next, the belt 2a of the intermediate transfer member 2 which is in contact with the yellow toner image is applied with a high voltage on a corona discharger, a metal roller, or a conductive roller in which carbon or the like is mixed into a synthetic resin. Transfer is performed by the intermediate transfer device 11 configured to apply a high voltage.

Residual toner that has not been transferred from the photosensitive member 1 to the belt 2a of the intermediate transfer member 2 is cleaned by the cleaning device 6, and the photosensitive member 1 is refreshed and used for forming a latent image of the next color component. Similarly, the same process is repeated for each color component, and the belt 2 of the intermediate transfer member 2 is repeated.
Obtain a composite image on a.

On the other hand, the transfer material 13 sent out from the transfer cassette 12 is aligned with the composite image obtained on the belt 2a of the intermediate transfer body 2 by the registration roller 8, and the transfer material 13 of the intermediate transfer body 2 and the transfer device 5 is aligned. It is conveyed to the transfer section in between. The composite image on the belt 2a of the intermediate transfer member 2 is collectively transferred onto the transfer material 13 by the transfer device 5, which is a corona discharger to which a high voltage is applied. The composite image collectively transferred onto the transfer material 13 is guided to the fixing device 10 and is fixed onto the transfer material 13 by heat and pressure.

The toner of the composite image which is not completely transferred to the transfer material 13 by the transfer device 5 is the belt 2 of the intermediate transfer member 2.
The residual toner remains on the surface a, but the residual toner is cleaned and refreshed by the cleaning device 9. The cleaning device 9 is the belt 2a of the intermediate transfer member 2.
The intermediate transfer member 2 is at a position separated from the belt 2a until one combined image is obtained, and the combined image is transferred to the transfer material 13 by the transfer device 5. After the transfer, the contact state is established and the residual toner is cleaned.

[0013]

In such a conventional image forming apparatus, since the residual toner on the intermediate transfer body 2 is cleaned by the cleaning device 9 capable of separating and contacting the intermediate transfer body 2, the separating / contacting mechanism is used. Is required and it becomes mechanically complicated,
There is a problem that the cost is high and the device becomes large. In addition, since the intermediate transfer body 2 receives an impact when the cleaning device 9 is separated from and contacted with the cleaning device 9, there is a problem in that the speed of the intermediate transfer body 2 fluctuates, a positional deviation occurs in the toner overlapping state, and the image is disturbed. It was

Therefore, the present invention solves the above problems, and an object of the present invention is to provide a small-sized, low-cost color image forming apparatus which can always obtain stable and good images.

[0015]

To this end, the present invention comprises exposure means for irradiating the latent image carrier surface with a light image decomposed into color components to form an electrostatic latent image for each color component. Developing means for individually developing the electrostatic latent image of each color component with the developer of each color component to form a visible image, and the developed image on the photoconductor are sequentially transferred onto the intermediate transfer member and synthesized. An intermediate transfer unit for forming an image, a transfer unit for transferring the composite image onto a transfer material, and a cleaning unit for cleaning the toner adhering to the photosensitive member,
The residual toner on the intermediate transfer member is reattached to the photosensitive member to clean the surface of the intermediate transfer member, and the toner reattached to the photosensitive member is cleaned by the cleaning unit.

[0016]

With the above structure, since the residual toner on the intermediate transfer member is re-adhered to the photosensitive member for cleaning, a cleaning device having a complicated structure for cleaning the intermediate transfer member is not required, and the cleaning operation is greatly reduced. The cost can be reduced, the size can be reduced, and the configuration can be simplified. Further, it is possible to obtain a good image without the displacement of the toner due to the impact of separation and contact of the cleaning device.

[0017]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram of a color image forming apparatus according to this embodiment. The same parts as those of the conventional apparatus shown in FIG. The characteristic structure of this embodiment is that the photosensitive member 1 and the intermediate transfer member 2 described in the conventional apparatus are used.
By applying a bias having a reverse polarity to the toner to the photoconductor 1 and a bias having the same polarity as the toner to the intermediate transfer body 2 at the contact portion of 1 to reattach.

That is, reference numeral 15 in FIG. 1 denotes a charger installed so as to face the belt 2a of the intermediate transfer member 2 and open, and charges the residual toner on the belt 2a.
Reference numeral 16 denotes a photoconductor bias switch for applying a bias having a polarity opposite to that of the toner to the photoconductor 1 at the contact portion between the photoconductor 1 and the intermediate transfer body 2. Reference numerals 17a and 17b denote intermediate transfer member bias switches for applying a bias to the intermediate transfer member 2 at the contact portion between the photosensitive member 1 and the intermediate transfer member 2. 17
When the intermediate transfer member bias switch a is turned on, a positive bias is applied, and when the intermediate transfer member bias switch 17b is turned on, a negative bias is applied.

The operation of the above embodiment will be described below. The image forming operation is the same as that of the conventional apparatus. After the image forming operation is completed, the residual toner on the intermediate transfer body 2 which has not been transferred to the transfer material 13 by the transfer device 5 is charged by the residual toner charger 15
Is charged to the same polarity as the toner (in this embodiment, it is assumed that the toner is negatively charged). The charged residual toner is reattached to the photoconductor 1 by applying a positive bias to the photoconductor 1 by turning on the photoconductor bias switch 16 at the contact portion between the photoconductor 1 and the intermediate transfer member 2. .. Further, during the image forming operation, the intermediate transfer member bias switch 17a is in the ON state, and the positive bias is applied to the intermediate transfer member 2, so that the toner negatively charged on the photosensitive member 1 is transferred to the intermediate transfer member 2. After the image forming operation is completed, a negative bias is applied to the intermediate transfer body 2 by turning off the intermediate transfer body bias switch 17a and turning on the intermediate transfer body bias switch 17b. Therefore, the residual toner that has been negatively recharged by the residual toner charger 15 on the intermediate transfer body 2 is repelled, and is more likely to be reattached on the photosensitive body 1 than on the intermediate transfer body 2. The residual toner redeposited on the photoconductor 1 is cleaned by the cleaning device 6.

Therefore, the residual toner on the intermediate transfer member 2 is reattached to the photosensitive member 1 and cleaned to clean the intermediate transfer member 2 by a cleaning device 9 for the intermediate transfer member 2.
Can be eliminated, and the cost of the device can be reduced and the device can be downsized.

A cleaning device 9 for the intermediate transfer member 2
When the blade is composed of a blade such as urethane, residual toner remains as a streak of the blade after the contact and separation from the intermediate transfer body 2, but this residual toner may cause toner drop and image disturbance. In that case, residual toner can be removed by performing cleaning in the same manner as in the above embodiment, and a good image without toner loss or image disturbance can always be obtained.

[0022]

As described above, according to the present invention,
Exposure means for irradiating the surface of the latent image carrier with a light image separated for each color component to form an electrostatic latent image for each color component; and an electrostatic latent image for each color component, a developer for each color component. Developing means for individually developing a visible image on the photoconductor, an intermediate transfer means for sequentially transferring the visible images on the photoconductor onto the intermediate transfer body to form a composite image, and the composite image as a transfer material. A transfer means for transferring and a cleaning means for cleaning the toner adhering to the photosensitive member, and the residual toner on the intermediate transfer member is re-adhered to the photosensitive member to clean the surface of the intermediate transfer member. Since the color image forming apparatus is configured so that the toner re-adhered to the body is cleaned by the cleaning means, it is possible to eliminate the need for a cleaning apparatus for the intermediate transfer body, which involves a separating / contacting mechanism, and reduce the cost of the apparatus. Miniaturization and simplification of equipment It can always be obtained good image achieving.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a color image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a conventional color image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor (latent image carrier) 2 Intermediate transfer body 2a Belt 6 Cleaning device 15 Residual toner charger 16 Photoconductor bias switch 17a Intermediate transfer body bias switch 17b Intermediate transfer body bias switch

Claims (4)

[Claims] 1. An exposure device for irradiating a surface of a latent image carrier with a light image separated for each color component to form an electrostatic latent image for each color component, and an electrostatic latent image for each color component for each color. Developing means for developing with a developer for each component to individually form a visible image; intermediate transfer means for sequentially transferring the developed images on the photoreceptor onto the intermediate transfer body to form a composite image; A transfer unit that transfers an image to a transfer material and a cleaning unit that cleans the toner that adheres to the photoconductor are provided, and the residual toner on the intermediate transfer unit is reattached to the photoconductor and the surface of the intermediate transfer unit is A color image forming apparatus, comprising: cleaning and re-adhering toner on the photoconductor by the cleaning unit. 2. When the residual toner on the intermediate transfer member is redeposited on the photosensitive member, a bias having the same polarity as the toner is applied to the intermediate transfer member at the contact portion between the photosensitive member and the intermediate transfer member. The color image forming apparatus according to claim 1, wherein: 3. When the residual toner on the intermediate transfer body is redeposited on the photosensitive body, a bias having a polarity opposite to that of the toner is applied to the photosensitive body at a contact portion between the photosensitive body and the intermediate transfer body. The color image forming apparatus according to claim 1, wherein: 4. The residual toner on the intermediate transfer body is charged by a residual toner charger before the redeposited residual toner on the intermediate transfer body on the photosensitive body. The described color image forming apparatus.